8-forces and machines

forces and machines
examples:
Which of these objects has a screw?
a-bottle cap
b-ramp (for disabled people in wheel chair)
c-saw
d-ladder

This is a non-contact force:
a-frictional force
b-gravitational force
c-normal force
d-spring force

1.This is a non-contact force:

a) gravity

b) electric forces

c) magnetic force

d) all of them are correct

2.What changes does acceleration produce?

a) speed

b) direction

c) both of them are correct

d) none of them is correct

3.Choose all the machines : Not valid, only one correct answer

a) washing machine

b) car

c) hanger

d) handbag

4.Choose the one which is not a simple machine

a) pulley

b) inclined plane

c) screw

d) computer

5.Cross out the incorrect sentence:

a) The bicycle is a complex machine

b) In a bicycle pedals are levers

c) In a bicycle the handlebar is a pulley

d) In a bicycle the chain is a pulley

6.Engine is:

a) a simple machine that turns kinetic energy into movement

b) a simple machines that turns movement into energy

c) a complex machine that turns any energy into movement

d) a simple machine that turns wind into movement

7.What type of force requires two pieces?

a) simple force

b) contact-force

c) non- contact force

d) gravity

8.What is speed?

a) velocity

b) measurement

c) is a measurement of how fast an object moves relative to a reference point.

d) a and c are true

9.What force is what keeps us on Earth?

a) motion

b) gravity

c) anything

d) friction

10.What two concepts takes into account the acceleration?

a) velocity and speed

b) time and velocity

c) speed and direction

d) motion and time

11.How many objects have to be in contact for friction to occur?

a) 2

b) 4

c) 5

d) 1

12. A complex machine :

a) has three pieces and works as electric energy, like home appliances

b) has more than two pieces and has some complex machines

c) turns energy into movement

d) has one piece

13. Why does a ball stop on the floor without somebody´s intervention?

a) It loses its force

b) because of friction

c) because of gravity

d) it crashes into a rock

14. What happens if we throw a ball downward out of a window?

a) speed starts to increase

b) speed doesn´t change

c) speed decreases

d) it doesn´t move

15.How does a inclined plane work? confusing

a) it can elevate an object with less friction

b) it can elevate an object quickly

c) it can elevate an object not using less force

d) it can elevate an object slowly

16. Choose the ones that are simple machines: only one answer

a) wedge

b) bycicle

c) motor

d) lever

17. What other material besides solids can cause friction?

a) gravity

b) air

c) anything

d) wind

18. Screws can be used:I think this is confusing

a) to pull two pieces of wood together and hold them in place

b) to join two metal materials

c) to join a wheel

d) to join to objects

19. The inclined plane consists of:

a) a flat surface that forms an obtuse angle with the ground

b) a flat surface that forms an acute angle with the ground

c) a curved surface that forms an acute angle with the ground

d) straight curve surface that forms an obtuse angle

20. When you screw a hinge into a door:

a) the input forces is used

b) the output forces is used

c) no force is used

d) nothing happens